Moby Dick coming together - GT-R Register - Official Nissan Skyline and GTR Owners Club forum

kismetcapitan · 13th June 2008, 02:57 AM

after a lot of distraction (moving my business and home, lots of work, bike interests, etc), the car, literally forgotten for a bit, is now coming together. All machining is now done and all that's left is assembly after the final parts come in (Cosworth bearings and Cosworth piston wrist pins). Should have the car ready to run in by next weekend - I am having my bearings overnighted!

new crankshaft

we used a sacrificial set of OEM bearings (yellow grade) to get exact measurements. Bearings have been ordered to match (the yellows are too thick and there's inconsistency in the block mains meaning I need a mixed set) so that every crank and rod journal has a .038~.040mm oil film thickness. Even though the crank is new, the block is not, and just like my old block, there's this oddity where the back three plus main journal are the same, but the front three are looser, requiring thicker bearings to match clearances. I get the sense that the RB26 crankshaft likes to wiggle its willy up front, which cannot possibly be good for the oil pump, and so I'm glad I'm now running an ATI Damper.

measuring journals:

finally, a builder who takes the time to check every last damned bit of an engine.

checking every last piece:

the piston wrist pins have runout, so a new set was ordered. HKS would be the matching replacement, but I chose Cosworth for convenience, lighter weight, cheaper price, and perceived higher brand quality. Not much to a wrist pin really, just a 21mm x 60mm metal rod. But if this engine is going to be done in a perfectionist manner, then pull out all the stops. My builder has instructions to check and perfect everything, down to the last bolt, nut, circlip, absolutely everything. The runout check was during balancing all the conrod/piston bits.

excessive clutch cover pressure plus worn thrust bearing surface =

although in this case, it wasn't so much the center main bearing as it was an old and well-worn crankshaft. If this tiny crack had not developed, I would have never discovered this problem:

JUN oil pump gear, cracked in half. However, the pump never gave any symptoms of failure, and held itself together without shattering for months of driving. So I'm both impressed/dismayed by JUN - sucks that it broke, but impressed that even though the pump was hammered and broke, it still worked flawlessly. Again, I watch oil pressure like a hawk, and it never gave a hint of anything wrong, other than a dribble of oil from the pump housing. Replacement is a Tomei.

this will blow your mind:

#1 and #2 conrod bearings spun. This occurred one year ago, when I got a subtle rattle in the death zone for bearings (3000rpm) after hard running on Motul 5W-30. A switch to Castrol 0W-40 and pulling 10 degrees of timing in the offload 3000-5000rpm zone "cured" the problem, and after a couple months, I was able to return timing to normal and the car ran fine. But there's the damage anyways. Anyways, from here on out, I'm done with thin oil - no reason to risk it, and I will run Castrol TWS 10W-60 until the day I die.

I have pictures to be uploaded yet of the block and head; the head has been ported and flowed on both intake and exhaust ports and the exhaust manifolds (stock, the best possible choice) ported a touch and mummy-wrapped. The block has a new hone that is like an engine-turned watchface - dead-perfect. I suppose I could have reused my piston rings, but with a hone job that good, new HKS rings were procured.

I have decided to run this engine in progressively and get lots of time with mineral oil before switching over to synthetic. Mick was kind enough to share his run-in formula, very straightforward actually. I'm actually a bit swayed by BMW Motorrad's run-in schedule, that absolutely forbids synthetic use for TEN THOUSAND MILES, as they claim it takes that long for the pistons and cylinders to truly mate up.

Ten days, then I finally get to drive my baby again! With work allowing me no driving time (I walk five minutes from home to work) and the bulk of my recreational time spent tearing up the roads on my bike, I suspect this engine will take literally months to finish up 1000 miles and be ready for some dyno pulls!

andy42uk · 13th June 2008, 04:01 PM

Thank you for the update and pictures.
Please keep us all informed of your progress.
Andy.

rasonline · 13th June 2008, 04:59 PM

interesting abot the oil.. if i remember correctly, your last oil that you were using was 0W20??

kismetcapitan · 13th June 2008, 05:04 PM

I'm feeling good about the Cosworth bits - they are new in the bearing business, but the company itself has a lot behind that name! Their bearings are similar to ACL - no flash coating, just hard trimetal shells. But its true that there are very few RBs running Cosworth bearings so far.

kismetcapitan · 13th June 2008, 05:15 PM

Quote:

Originally Posted by rasonline

interesting abot the oil.. if i remember correctly, your last oil that you were using was 0W20??

yep. I grossly misunderstood something about oil, or at least I think I did. I had incredible and consistent oil pressures, but the oil film tension of the thin stuff is weaker than thick oil, flow or no flow. So oil pressure is just one part of the equation - it's clear that thin oil under pressure was not enough to keep my front bearings (which were out of spec thanks to the last jackass builder) from touching the crank.

My guess is that thick oil might help compensate for slight oil clearance irregularities and help the crank float better. Even at 8 bars pressure, I don't think 0W-20 at over 100 degrees was good for my particular engine due to the mismatched bearings. Race engines built with exacting tolerances can probably run the stuff, but even though I am taking extreme pains to keep oil clearances on all bearings at a rigorous spec of 0.038~0.040mm (only 0.002mm deviation permitted), I won't risk it again.

btw, I can't even fathom a 0.002mm difference. Back when I used to build and repair guitars alot, I could feel out a .005 INCH difference, but that was the limit. Sharp eyes with the Plastigage and that fancy measuring equipment I guess!

blue32 · 13th June 2008, 05:17 PM

i can see this is going to be a good thread, keep it up matey

Ryan

paul cawson · 13th June 2008, 05:30 PM

Dont forget to drill out the oil way plugs, I found quite a lot of old shell bits in mine

Rain · 13th June 2008, 05:39 PM

Cant wait to see how it turns out T, keep this thread going !

freakazoid3 · 13th June 2008, 11:17 PM

Quote:

Originally Posted by paul cawson

Dont forget to drill out the oil way plugs, I found quite a lot of old shell bits in mine

He's got a new crank, so surely that's not necessary?

Don't want to be the smart-ass around here though

tarmac terror · 14th June 2008, 10:48 AM

Should be an interesting thread....

Although I would say to you dont obsess about things that dont require obsession. Concentrate on the bits that do. Its true that 'proper' engine building requires an attention to detail especially in the bearing dept but its also true that most of it can be 'whacked together'

The type of hone is important too. Different car manufacturers have different methods and specs of honing new engines. You'd be wise to do your run-in with a nod to how it was honed.

I do think though that with this engine build you maybe need to take a step back and breathe.....You mentioned before that the last engine builder had OCD but I suspect that you may have a similar condition.

Hope it all goes well though.

TT

kismetcapitan · 15th June 2008, 03:14 AM

correction - this builder has OCD, the one who built my engine before just slapped the thing together.

I am being a bit obsession, but I also do push my engine hard. A new crank wasn't mandatory, but I was concerned about crank thrust.

OCD? I'm now in a total mess mentally because I can't decide to use 120 gram piston wrist pins, or hold up the build and wait for 100 gram pins.

paul cawson · 15th June 2008, 04:39 AM

Quote:

Originally Posted by freakazoid3

He's got a new crank, so surely that's not necessary?

Don't want to be the smart-ass around here though

Its the plugs in the block I mean, where the oil and water pumps meet there is a plug to the otherwise unclean able chamber. Lots of shell bits hide in here only to come out later and chew up your new build

pupsi · 15th June 2008, 10:23 AM

Nice going Toby, good luck.

kismetcapitan · 15th June 2008, 01:44 PM

Quote:

Originally Posted by paul cawson

Its the plugs in the block I mean, where the oil and water pumps meet there is a plug to the otherwise unclean able chamber. Lots of shell bits hide in here only to come out later and chew up your new build

is that chamber an oil or water chamber (that gets accessed from the plug)?

psd1 · 15th June 2008, 02:23 PM

Wow, I gotta give you an "A" for tenacity...how many times will this be that the motor has been apart?

13th June 2008, 02:57 AM	#1 (permalink)
kismetcapitan GTR Register Member Join Date: Nov 2005 Location: Seoul Korea Posts: 6,393	Moby Dick coming together after a lot of distraction (moving my business and home, lots of work, bike interests, etc), the car, literally forgotten for a bit, is now coming together. All machining is now done and all that's left is assembly after the final parts come in (Cosworth bearings and Cosworth piston wrist pins). Should have the car ready to run in by next weekend - I am having my bearings overnighted! new crankshaft we used a sacrificial set of OEM bearings (yellow grade) to get exact measurements. Bearings have been ordered to match (the yellows are too thick and there's inconsistency in the block mains meaning I need a mixed set) so that every crank and rod journal has a .038~.040mm oil film thickness. Even though the crank is new, the block is not, and just like my old block, there's this oddity where the back three plus main journal are the same, but the front three are looser, requiring thicker bearings to match clearances. I get the sense that the RB26 crankshaft likes to wiggle its willy up front, which cannot possibly be good for the oil pump, and so I'm glad I'm now running an ATI Damper. measuring journals: finally, a builder who takes the time to check every last damned bit of an engine. checking every last piece: the piston wrist pins have runout, so a new set was ordered. HKS would be the matching replacement, but I chose Cosworth for convenience, lighter weight, cheaper price, and perceived higher brand quality. Not much to a wrist pin really, just a 21mm x 60mm metal rod. But if this engine is going to be done in a perfectionist manner, then pull out all the stops. My builder has instructions to check and perfect everything, down to the last bolt, nut, circlip, absolutely everything. The runout check was during balancing all the conrod/piston bits. excessive clutch cover pressure plus worn thrust bearing surface = although in this case, it wasn't so much the center main bearing as it was an old and well-worn crankshaft. If this tiny crack had not developed, I would have never discovered this problem: JUN oil pump gear, cracked in half. However, the pump never gave any symptoms of failure, and held itself together without shattering for months of driving. So I'm both impressed/dismayed by JUN - sucks that it broke, but impressed that even though the pump was hammered and broke, it still worked flawlessly. Again, I watch oil pressure like a hawk, and it never gave a hint of anything wrong, other than a dribble of oil from the pump housing. Replacement is a Tomei. this will blow your mind: #1 and #2 conrod bearings spun. This occurred one year ago, when I got a subtle rattle in the death zone for bearings (3000rpm) after hard running on Motul 5W-30. A switch to Castrol 0W-40 and pulling 10 degrees of timing in the offload 3000-5000rpm zone "cured" the problem, and after a couple months, I was able to return timing to normal and the car ran fine. But there's the damage anyways. Anyways, from here on out, I'm done with thin oil - no reason to risk it, and I will run Castrol TWS 10W-60 until the day I die. I have pictures to be uploaded yet of the block and head; the head has been ported and flowed on both intake and exhaust ports and the exhaust manifolds (stock, the best possible choice) ported a touch and mummy-wrapped. The block has a new hone that is like an engine-turned watchface - dead-perfect. I suppose I could have reused my piston rings, but with a hone job that good, new HKS rings were procured. I have decided to run this engine in progressively and get lots of time with mineral oil before switching over to synthetic. Mick was kind enough to share his run-in formula, very straightforward actually. I'm actually a bit swayed by BMW Motorrad's run-in schedule, that absolutely forbids synthetic use for TEN THOUSAND MILES, as they claim it takes that long for the pistons and cylinders to truly mate up. Ten days, then I finally get to drive my baby again! With work allowing me no driving time (I walk five minutes from home to work) and the bulk of my recreational time spent tearing up the roads on my bike, I suspect this engine will take literally months to finish up 1000 miles and be ready for some dyno pulls! Last edited by kismetcapitan; 13th June 2008 at 03:03 AM.

13th June 2008, 05:39 PM	#8 (permalink)
Rain GTROC Member Join Date: Apr 2006 Posts: 1,842	Cant wait to see how it turns out T, keep this thread going ! __________________ 016 Project Deus Ex Machina - Endless-R GTR-32

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13th June 2008, 04:01 PM	#2 (permalink)
andy42uk GTR Register Member Join Date: Sep 2005 Location: Oxford Posts: 860	Thank you for the update and pictures. Please keep us all informed of your progress. Andy.

13th June 2008, 04:59 PM	#3 (permalink)
rasonline GTR Register Member Join Date: Mar 2005 Location: South-East Africa Posts: 1,501	interesting abot the oil.. if i remember correctly, your last oil that you were using was 0W20??

13th June 2008, 05:04 PM	#4 (permalink)
kismetcapitan GTR Register Member Join Date: Nov 2005 Location: Seoul Korea Posts: 6,393	I'm feeling good about the Cosworth bits - they are new in the bearing business, but the company itself has a lot behind that name! Their bearings are similar to ACL - no flash coating, just hard trimetal shells. But its true that there are very few RBs running Cosworth bearings so far.

13th June 2008, 05:17 PM	#6 (permalink)
blue32 GTROC Member Join Date: Jan 2007 Location: Midlands Posts: 301	i can see this is going to be a good thread, keep it up matey Ryan

13th June 2008, 05:30 PM	#7 (permalink)
paul cawson New Users Join Date: Jul 2003 Location: Essex Posts: 2,069	Dont forget to drill out the oil way plugs, I found quite a lot of old shell bits in mine

14th June 2008, 10:48 AM	#10 (permalink)
tarmac terror New Users Join Date: Jul 2003 Location: Hampshire, but Scottish through and through! Posts: 2,621	Should be an interesting thread.... Although I would say to you dont obsess about things that dont require obsession. Concentrate on the bits that do. Its true that 'proper' engine building requires an attention to detail especially in the bearing dept but its also true that most of it can be 'whacked together' The type of hone is important too. Different car manufacturers have different methods and specs of honing new engines. You'd be wise to do your run-in with a nod to how it was honed. I do think though that with this engine build you maybe need to take a step back and breathe.....You mentioned before that the last engine builder had OCD but I suspect that you may have a similar condition. Hope it all goes well though. TT

15th June 2008, 03:14 AM	#11 (permalink)
kismetcapitan GTR Register Member Join Date: Nov 2005 Location: Seoul Korea Posts: 6,393	correction - this builder has OCD, the one who built my engine before just slapped the thing together. I am being a bit obsession, but I also do push my engine hard. A new crank wasn't mandatory, but I was concerned about crank thrust. OCD? I'm now in a total mess mentally because I can't decide to use 120 gram piston wrist pins, or hold up the build and wait for 100 gram pins.

15th June 2008, 10:23 AM	#13 (permalink)
pupsi GTROC Member Join Date: Aug 2006 Location: West London Posts: 1,941	Nice going Toby, good luck.

15th June 2008, 02:23 PM	#15 (permalink)
psd1 GTR Register Member Join Date: May 2004 Posts: 1,812	Wow, I gotta give you an "A" for tenacity...how many times will this be that the motor has been apart?